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WU I g 0 99 unuoo ncrcnmut tXAMmt (No Model.) 4 Sheets-Sheet 1.

0. w. TOBEY. RHEOSTAT.

No. 480,151. Patented Aug. 2, 1892.

( m del.) 4 Sheets-Sheet 2.

C. W. TOBEY.

RHEOSTAT.

Patented Aug. 2, 1892i (No Model.) 4 Sheets-Sheet 3. G. W. TOBEY.

RHBOSTAT.

No. 480,151. Patented Aug. 2, 1892.

Wmwmwz- MW fiw A6. W e-Wu M M44 (No Model.) 4 Sheets-Sheet =4. C. W. TOBEY.

RHEOSTAT.

No; 480,151. Patented Aug. 2, 1892.

- ing is a full, clear, and exactdescription thereof, reference being had to the accompanying adapted for use with an electric light, portions tion for use with motors; Fig. 10, a section closing box or casing removed; and Fig. 12, a

. or vary the strength of acurrent as delivered stat and the parts thereof constructed and ar- .UNITED STATES PATENT OFFICE.

CHARLES w. Team, on NEW BEDFORD, MASSACHUSETTS, ASSIGNOR 'I()' BURT & TOBEY, or SAME PLACE.

:RHE'OSTAT.

srncrmcarron forming part of Letters Patent Nb. 480,151, dated August 2, 1892.

' Application tiled July 11, 1891.

To all whom it may concern:

Be it known that I, CHARLES l". TOBEY, of New Bedford, in the county of Bristol, and in the State of Massachusetts, have invented certain new and useful Improvements in Rheostats; and I do hereby declare that the follow drawings, in which- Figure 1 is a perspective view of a rheostat ot' the casing being shown as brokenawayto disclose the interior arrangement of parts. Figs. 2 to 4, inclusive, are detail views of the resistance device I employ. Fig. 5 is a plan view of the rheostatwith the casing-cover removed; ig. 6, a section on the line a: a: of Fig. 5.. 7 is a plan of the side opposite that shown in Fig. 5, the casing being omitted; Fig.8, a detail viewin perspective show-' ing the manner of connecting the several resistances; Fig. 9, a perspective view of a rheostat constructed in accordance with my inventhereof; Fig. ll, a bottom view with the indetail view in section on line 2 2, Fig. 10, showing the spring switch or brush employed with the motor form. A I

Letters of like name and kind refer to like parts throughout the several figures.

The object of my invention is to provide certain improvements in rheostats or current regulating and controlling devices for use in electric circuits whether in connection with electric lights, motors, or in other situations where it is desirable and necessary to control to its destined place for utilization; and to this end said invention consists in the rheorauged substantially as hcreinafterspecified.

Inthe drawings I show two forms of rheostats constructed in accordance with my invention as adapted for use with an electric mer being illustrated in Figs. 1 to 8 and the latter in Figs. 9 to 11, inclusive.

In constructing a rheostat for the purpose of regulating and controlling lights I employ No. 399,239. (No modehe fg a disk A, of porcelain or other non-conducting materiahand mount thereon in a circular linea series of resistances adapted from one to the whole series to be put into the circuit by means of a switch device hereinafter described,as well as means, also operatingin conjunction with said switch,whereby the circuit may be opened or closed and the current in the latter event not be modified bythepresence of the resistance devices. The several resist- 6: ances are constructed alike, each being in the form of acylindrical bodyconsisting of acomposition of inferior conductivity and a holder or casing for the same. This composition ismade of powdered graphite, (which is the con- 6 5 ductor,') cement, and asbestus in such proportions'as the degree of resistance desired'may dictate, which are thoroughly mixed with water and then combined with the holder or casing under pressure. If desired, however, clay or some othersuitable non-conducting material maybe used instead of the cement and asbestos, although these-latter are preferable, and, also said substances may be combined under pressure without being moistened by water. The asbestos is valuable not only because of its electrical non-conductivity and because of being a non-conductor of and refractory to heat, but also because, being fibrous, it serves to bind or hold the other ele- 8o "ments together, much as doesliair in plaster.

The holder consists of a cylindrical hollow metal body .or shall B, open at one end, in which the composition is placed, and a metal disk B, on which is a shank I), having the arrangement presently described. Only a portion of the composition is contained in the shell B, as such a quantity thereof is used as to entirely fill and extend beyond the same. Upon the projecting portion the .disk B. is 0 superimposed with its shank extended into and thoroughly embedded therein. To key or lock the composition in the shell, its wall is provided with several perforations 1), into which portions of the composition extend, and 9 5- for securing the same and the disk I) firmly to,- gather the shank b of the-latter has anumber of annular depressions b. v The shell and disk v are necessary to be used, because the composition has not such coherence as to enable its too shape to be preserved without some such assistance. The shank b extends into the portion of the composition contained in the shell' and at the center of the latter, but does not 5' touch the same, and the shell and disk are shot in contact, but separated by the composition. The current is thus compelled to pass through the resistance before reaching the metallic conductors.

.10 .Each resistance is attached to and sup- '26 wardly-exended arms on the plate. The heads of thescrews abut against the under face of the disk, For the accommodation of the series of resistances the disk has a slot a extending therethrough, in which they are a5 cated, and its size-is such that a space is leftbetween the adjacent portions of the disk and the resistances, through which there can bea circulation ofair to prevent excessive heating of parts when the resistances are put in v the circuit.

Electrical connection between the resistances is made by means of a metallic conducting-strip E, which is secured at one of its ends to the disk B'of the resistance-holder 35. and at its other'end has passed through it the nearest screw D-for securing the next adjacent resistance-supporting plate to the disk A. Said screw thus not only performs this mechanical function of connecting the parts,

40 bntalso is a partof the electrical connection between them.

The device is placed in the circuit whose current is to be controlled by having one conducting-wire thereof connected bya bindingpost f to a metal plate F, which is secured to the disk A and is in electrical connection ,withaswitch device capable of having contact with any one of the resistance-supporting plates and the other wire thereof connected by a so binding-post to the first resistance-supporting plate in the series. The switch device consists of a switch arm or brush G, constructed of two thin pieces of spring-brass superimposed one upon the other, attached to a shaft or arbor A, jonrnaled at the center of the disk and extending therefrom in a spiral curve with their free ends bearing yieldingly upon the contact-plates. The two pieces are socured to the shaft by being placed between as two collars g and g, one of which is pinned to the shaft and through both of which and the confined pieces between a pin 9 is passed. The shaft H passes through an opening in an extension of the contact-plate F, being. thus 6 5 in electrical connection therewith, and is jou rnaled at its end at the other side of the disk A by having such end reduced and contained order that the latter may 'of headed screws L and L,

tact said plate has a depressionf, into which the free end of the'switcharm prin gs or seats itself.

Owing to the manner of connecting the sev eral resistances, it will .be seen-that the first resistance will not be put injtothe'circuit until the switch-arm rests on the second resistance-supporting plate, and scion throughout the series a resistance does not come into the plate is in contact with the @s'w'i'tch-arm,

circuit until the next'adjaeentfsupporting- Thus should the switch-armibo in contact with the second plate 0 the course of the current will be through the first plate, the first resistance, the metal plate E, attached to the disk B thereon, the securing-'screw'D, then through the second plate to the-'switch-arm, but not through the second resistance. This arrangement renders it necessary to provide after the last resistance a contact-plate I, in be thrown into thecircuit. Such plate, preferably, is shaped similarly to the resistance-supporting plates 0 and is attached to the disk A in the same way and by one of its fastening-screws and a strip E, connected electrically with said last resistance; also, as a consequence of such arrangement the current will be turned full on when the switch-arm rests upon the first resistancesnpporting plate, as the resistance supported thereby is not thrown in until contact is made with the second plate, as above described.

The arrangement of the resistances being in a circular line, the contact-plates are given the shape of segments of a circle, and in consequence of this arrangement the, device is most compact, requiring but little room, and thus specially adapted for use with lamps.-

The mechanism constructed as' thus far described is contained in a circular'casing K, of porcelain or other insulating material, to whose bottom the disk Ais attached by means which pass through such bottom and said disk, and nuts on portions of the screws that project through the bottom. The disk A does not rest onthe bot tom; but they are kept apart, so that a space is left between them for the free circulation of air to reduce the temperature when the redistance-pieces Z and Z, through which the screws pass, and, too, for the formation of air-spaces the disk is of less diameter than the interior of the casing and has at various free passage of airinto and through the same,

sistances are 1n circuit by the use of tubular and to provide an air-space between the device and the object to which it may be attached the casing-wall K is extended beyond the bottom thereof, so that the edges of this wall and not the bottom will rest against such} object. Said wall at numerous points is provided with openings or notches k to admit the circulation of air between said bottom and the object to which the device may be attached.

A cylindrical cap M, seated on an annular shoulder on the casing K, covers the mechanism not inclosed by said casing, being provided at its center with an opening for the perature is reached will melt, and so-break the circuit. The melting of the strip occurs not from an excess of electricity passing through it, but by an overheating of the re sistance and communication of heat from it.

to said strip. This of course, when it occurs,- until remedied, will prevent further use of the --device as a rheostat; but it does not prevent its use as an ordinary switch, inasmuch as the circuit could still be-made through thefirst resistance-supporting and contact plate C and the switch-arm.

In applying. my ideas to the construction of a rheostat for use with motors I employ resistances constructed precisely as those for use with the lampdevice andarrangeithem also in a circular line. The plates 0, to which said resistances are connected, however, do not constitute the contact-plates for engagement by the switch; but said plates are socured to the under side of a flat piece of slate A or other insulating material by screws passing therethrough and through the slate into a series of segmental plates upon the upper side of said piece of slate. For each resistance-supporting plate thh're is a plate 0', The resistances are connected'electrieally by means of fusible metal strips E, which at one end are attached to the disk B' of the resistently be stated. The switch consists of a centrally-located shaft H, from which extends a radial arm 72?, that at its outer end has attached a bowed-spring contact plate or brush h for contacting with the series of segmental contact-plates C. Said brush on its plate-engaging face has aspring-tongue referred-to ribs on certain of the contactplates to prevent backward movement of the switch from otf said plates to the-plates of resistances are so arranged and connected that the first contact made after a forward movement from the cutting-out plate F',which ances in the circuit, and not, as in the case of the lamp form, to utilize the whole capacity dersteod, as it renders it impossible to throw of course, is undesirable. Continued movement of the switch successively cuts out the *pediment. h

To assist the contact between the switch or brush h and the contact-plates, the switchshaft is projected beyond the inner face of the piece of slate whereon is placed a coiled spring N, having one end bearing against'a collar 0, held on the shaft'by a nut P, with a the d'irectionnecess ject. 0n the shaft is a hand-wheel h for r'otating the same to move the. switch. The piece of slate is preferably square in shape and is placed in a square cast-iron frame Q, through a circular opening q in whichthe mechanism on the upper side of the slate promechanism on the under side of the piece of slate, except on one side, where a portion of one of the walls of the box is removed. The opening thus formed is closed by a piece q, depending from the frame Q, to which are secured in a properly-insulated manner two binding-posts Sand S. One of these bindingposts'is connected to the switch and the other to the last resistance, and to them are also attached the conductors from the motor and the source of energy. .All of the mechanism is h, which is adapted to engage with the above-i immediately preceding them. As the series ,80

any to accomplish thiso'b improvement is in the direction of "the arrow shown in Fig. 9, is to throw all of the resista of the current, the object of this will be un the full current at once to the motor, which,

resistances until the current is allowed to pass 4 through the instrument without unusual im- ,tendency-to force the shaft longitudinally in jects, which frame is screwed toa square castiron box or casing R, that incloses all of theance-holder and at the other to the resistance/thus carried by the frame Q and can be resupporting plate 0 by one of the attachingscrews thereof, which constitutes the electrical connection with the contact-plate C'. There is also the provision of a segmental cut-out plate F, corresponding to the similar plate F of the lamp rheostat and a plate I for placingthe last resistance in circuit. Boththe last-named plate I and the cut-out plate F', which, as in the lamp form, are adjacent, have depressions in their faces, and in the present instance these are bounded by abruptly-rising ribs, whose function will presmoved therewith from the box or casing.

The walls or sides of the box R are perforated at various points to admit a free passage of air thereto for cooling purposes. At its corners the box is Y provided with feet to hold it out of close contact with the object to which it may be attached. v I

Having thus described my invention, what I claim is--- I a 1. 'A resistance-conductor for electric currents, composed of powdered graphite and asbestus' compressed into a sobering compact body, substantially as and for the purpose specified. 1 V

- 2. A resistance-conductor for electriccurrents, consisting of a'composition of propor- 5 tionate parts of powdered graphite,asbestus,

and cement compressed into a cohering compact body, substantially as and for the pm .pose shown:-

- 3. A resistance-conductor for electric our to rents, consisting of a/coinposition of proportionate parts of powdered graphite, asbestns, and cement mixed with water and compressed into a cohering compact body,substantially as and for the purpose set forth. r 5 4. A resistance for electric currents, consisting of powdered graphite and anon-conductor compressed into a coherent body, to whose opposite ends are secured metallic pieces, sub stantially as and for the purpose described. 2o 5. A resistance for electric currents, consisting of powdered graphite compressed .into a metal holder in a cohering body, which holder but partially inclosesthe same and constitutes means for its attachment to a support,

2 5 substantially as and for the purpose specified.

' 6. In combination with the resistance com- .position, the holder therefor, consisting of a shell or casing partly inclosing the same, and

' the disk or piece aflixed to such composition, substantially as and forthe purpose shown.

' 7. Incombination, theresistance composition' and the holder therefor, consisting of ashell or casing partlyinclosing the same and the disk with a shank aflixed thereto, united to such composition by havingsuch "shank embedded therein, substantially as and for the surpose set forth. Y

8. A resistance for electric currents, consisting of powdered graphite, asbestns, and cemg 0 out compressed and united with a holder con-"' placing any number from-one to the whole,

series in the circuit, substantially asand for the purpose specified. r

10. In combination with several resistances, the fusible conductorconnecting them, subslantially as and for the purpose set forth.

'11. In combination with the resistance de- 5 5 vice of a rheostat forming part of, a circuit, a fusible conductor connected directly to said resistance and also forming a part of the circuit, substantially as and for the purpose specified. 12. In combination, the several resistances, the supporting-plate for each resistance, acting as a contact, the body to which said plates are attached, the attaching-screws,- and the fusible conducting'strip extending from one '65 resistance to one of the attaching-screws of the next adjacent resistance, substantially as and for the purpose set forth. 7 7

1 3. In combination, the supporting-body of insulating material having a slot or opening, the series of resistances in the latter, the contact-plates for said resistances, from which the same are supported, and the switch, substantially as and for the purpose shown.

14. In combin'ation,theseries of resistances, their contacts, the circuit-closing contact, the cut-out contact, said contacts being arranged in a circle with the last-named twoadiacent to each other, and the spring-switch, said cntout contact having a depression to seat said s'witch, substantially as and for the purpose described. a A

15. In a switch, in combination withthe spring movable brush or contact device, the circuit-closing contact and the cut-out contact having a depression for seating said brush, substantially as and for the purpose specified.

In testimony that I claim the foregoing I have hereunto set my hand this 22d day of I June, A. D. 1891.

' CHARLES W. TQBEY.

Witnessem" Wu. F. CASWELL, Emma D. CASWELL. 

